Vertical batch furnace assembly comprising a cooling gas supply

ABSTRACT

A vertical batch furnace assembly, comprising a core tube, an outer casing, a cooling chamber bounded and enclosed by the outer casing and the core tube, and at least one cooling gas supply emanating in the cooling chamber. The core tube has an elongated circumferential wall extending in a longitudinal direction, and is configured to accommodate wafers for processing in the vertical batch furnace. The outer casing extends around the core tube and comprises a heating element for applying a thermal treatment to wafers accommodated in the core tube. The at least one cooling gas supply comprises at least one cooling gas supply opening which is arranged such that the cooling gas enters the cooling chamber with a flow direction which is substantially tangent to the circumferential wall.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationSer. No. 63/014,993 filed Apr. 24, 2020 titled VERTICAL BATCH FURNACEASSEMBLY COMPRISING A COOLING GAS SUPPLY, the disclosure of which ishereby incorporated by reference in its entirety.

FIELD OF THE DISCLOSURE

The present disclosure generally relates to a vertical batch furnaceassembly comprising a cooling gas supply.

BACKGROUND

Most vertical batch furnaces are provided with a core tube configured toaccommodate wafers to be processed in the vertical batch furnace. Duringa treatment in the vertical batch furnace the wafers and core tube mayget hot. In order to speed up the throughput of the vertical batchfurnace assembly, the core tube may be cooled down. Cooling gas may besupplied from a number of circumferentially spaced openings at a lateralside of a cooling chamber between the circumferential wall of the coretube and an outer casing.

SUMMARY

This summary is provided to introduce a selection of concepts in asimplified form. These concepts are described in further detail in thedetailed description of example embodiments of the disclosure below.This summary is not intended to identify key features or essentialfeatures of the claimed subject matter, nor is it intended to be used tolimit the scope of the claimed subject matter.

It may be realized that circumferentially spaced openings may locallyproduce cold spots on the circumferential wall of the core tube. Suchcold spots may cause temperature differences within the circumferentialwall, which may lead to stresses in said circumferential wall.Furthermore, the wafers inside the core tube may also be exposed totemperature differences which may lead to breaking of said wafers.

Therefore, it may be an object to provide a vertical batch furnaceassembly in which the above mentioned problems may be alleviated.

To that end, there may be provided a vertical batch furnace assemblyaccording to claim 1. More particularly, there may be provided avertical batch furnace assembly comprising a core tube, an outer casing,a cooling chamber bounded and enclosed by the outer casing and the coretube, and at least one cooling gas supply emanating in the coolingchamber. The core tube may have an elongated circumferential wallextending in a longitudinal direction, and the core tube may beconfigured to accommodate wafers for processing in the vertical batchfurnace. The outer casing may extend around the core tube and maycomprise a heating element for applying a thermal treatment to wafersaccommodated in the core tube. The cooling gas supply may comprises atleast one cooling gas supply opening which is arranged such that thecooling gas enters the cooling chamber with a flow direction which issubstantially tangent to the circumferential wall.

There may also be provided a method for cooling a vertical batch furnaceaccording to claim 16. More particularly, there may be provided a methodcomprising providing a vertical batch furnace 10 according to thedescription, and supplying a cooling gas in the cooling chamber 20 witha flow direction which is substantially tangent to the circumferentialwall. The substantially tangent flow direction may include an angle withthe longitudinal direction of the elongated circumferential wall 14 inthe range of 90°±15° and may include an angle in the range of 0°±10°with a plane through a point of the circumferential wall that is closestto a said respective cooling gas supply opening and that is tangentialto the circumferential wall.

For purposes of summarizing the invention and the advantages achievedover the prior art, certain objects and advantages of the invention havebeen described herein above. Of course, it is to be understood that notnecessarily all such objects or advantages may be achieved in accordancewith any particular embodiment of the invention. Thus, for example,those skilled in the art will recognize that the invention may beembodied or carried out in a manner that achieves or optimizes oneadvantage or group of advantages as taught or suggested herein withoutnecessarily achieving other objects or advantages as may be taught orsuggested herein.

Various embodiments are claimed in the dependent claims, which will befurther elucidated with reference to an example shown in the figures.The embodiments may be combined or may be applied separate from eachother.

All of these embodiments are intended to be within the scope of theinvention herein disclosed. These and other embodiments will becomereadily apparent to those skilled in the art from the following detaileddescription of certain embodiments having reference to the attachedfigures, the invention not being limited to any particular embodiment(s)disclosed.

BRIEF DESCRIPTION OF THE FIGURES

While the specification concludes with claims particularly pointing outand distinctly claiming what are regarded as embodiments of theinvention, the advantages of embodiments of the disclosure may be morereadily ascertained from the description of certain examples of theembodiments of the disclosure when read in conjunction with theaccompanying drawings, in which:

FIG. 1 shows an example of the vertical batch furnace assembly accordingto the description;

FIG. 2 shows upside-down view of a top part of the outer casing of theexample of FIG. 1 ;

FIG. 3 schematically shows an exploded perspective view of a detail ofFIG. 2 ; and,

FIG. 4 schematically shows a cross sectional view of an example of anend part of a cooling gas inlet tube according to the description.

DETAILED DESCRIPTION OF THE FIGURES

In this application similar or corresponding features are denoted bysimilar or corresponding reference signs. The description of the variousembodiments is not limited to the example shown in the figures and thereference numbers used in the detailed description and the claims arenot intended to limit the description of the embodiments, but areincluded to elucidate the embodiments.

Although certain embodiments and examples are disclosed below, it willbe understood by those in the art that the invention extends beyond thespecifically disclosed embodiments and/or uses of the invention andobvious modifications and equivalents thereof. Thus, it is intended thatthe scope of the invention disclosed should not be limited by theparticular disclosed embodiments described below. The illustrationspresented herein are not meant to be actual views of any particularmaterial, structure, or device, but are merely idealized representationsthat are used to describe embodiments of the disclosure.

As used herein, the term “wafer” may refer to any underlying material ormaterials that may be used, or upon which, a device, a circuit, or afilm may be formed.

In the most general term the present disclosure may provide a verticalbatch furnace assembly 10. The vertical batch furnace assembly 10 maycomprise a core tube 12, an outer casing 16, a cooling chamber 20bounded on a radial outer side by the outer casing 16 and on a radialinner side by the core tube 12, and at least one cooling gas supplyemanating in the cooling chamber 20. The core tube 12 may have anelongated circumferential wall 14 extending in a longitudinal directionL, and the core tube 12 may be configured to accommodate wafers forprocessing in the vertical batch furnace assembly 10. The outer casing16 may extend around the core tube 12 and may comprise a heating element18 for applying a thermal treatment to wafers accommodated in the coretube 12. The cooling gas supply may comprise at least one cooling gassupply opening 26 which is configured such that the cooling gas entersthe cooling chamber 20 with a flow direction which is substantiallytangent to the circumferential wall 14. The substantially tangent flowdirection may include an angle with the longitudinal L direction of theelongated circumferential wall 14 in the range of 90°±15°. Thesubstantially tangent flow direction may include an angle in the rangeof 0°±10° with a plane through a point of the circumferential wall 14that is closest to said respective cooling gas supply opening 26 andthat is tangential to the circumferential wall 14.

With a flow direction of gas out of the gas supply opening 26 which isat least initially tangent to the circumferential wall 14, the coolinggas will not immediately flow along the longitudinal direction of theelongated circumferential wall 14, but instead will spread out in atangential direction of the circumferential wall 14. Only after thecooling gas has spread out in the tangential direction of thecircumferential wall 14, the cooling gas will flow along thelongitudinal direction L of the elongated circumferential wall 14 asindicated with arrow F in FIG. 1 . By first distributing the cooling gastangentially, the circumferential wall 14 is more uniformly cooled. Inthis way, no cold spots are formed, and the disadvantages associatedwith these so-called cold spots are prevented.

In an embodiment, of which an example is shown in exploded view in FIG.3 , each cooling gas supply may comprise a cooling gas inlet tube 22 ofwhich an end part 24 extends into the cooling chamber 20. Said end part24, also shown in FIG. 4 , may be provided with the at least one coolinggas supply opening 26. Each cooling gas inlet tube 22 may be made of onepiece. Each cooling gas inlet tube 22 may be made of a ceramic material.An axial end 28 of the cooling gas inlet tube 22 extending into thecooling chamber 20 may be closed off.

In the example shown in FIG. 4 , the cooling gas inlet tube 22 extendsinto the cooling chamber 20. The cooling gas inlet tube 22 may extendthrough an opening 44 in the outer casing 16. By having the axial end 28of the cooling gas inlet tube 22 closed off, the cooling gas may beprevented from entering the cooling chamber 20 parallel to thelongitudinal direction of the elongated circumferential wall 14. The endpart of the shown cooling gas inlet tube 22 is provided with two coolinggas supply openings 26. Each supply opening is orientated such thatcooling gas entering the cooling chamber 20 via said opening enters thecooling chamber 20 tangentially with relative to the circumferentialwall 14. The cooling gas inlet tube 22 may be provided with a cam 46arranged to cooperate with a corresponding recess 48 in the outer casing16, which recess 48 is part of the opening 44 through which the coolinggas inlet tube 22 extends. The combination of the cam 46 on the coolinggas inlet tube 22 and the recess 48 in the outer casing 16 fixates theorientation of the cooling gas inlet tube 22 with respect to the outercasing 16 and thus also to the vertical batch furnace assembly 10 andthe core tube 12. This may ensure that the cooling gas supply openings26 will have the correct orientation with respect to the core tube 12 sothat the cooling gas will enter the cooling chamber 20 having a flowdirection which is substantially tangent to the circumferential wall 14.

The cooling gas inlet tube 22 may be heated during the treatment of thewafers in the core tube 12. The supplied cooling gas may lead to a bigdrop in temperature of the cooling gas inlet tube 22, when the coolingcommences. This drop in temperature may lead to internal stress in thecooling gas inlet tube 22. By embodying the cooling gas inlet tube 22 asone integral part, there are no fragile joints in the cooling gas inlettube 22 which may cause a breaking of the cooling gas inlet tube 22caused by this internal stress. Preferably, each cooling gas inlet tube22 is made of ceramic material. Ceramic material is able to withstandboth high temperatures and large temperature fluctuations. This makesceramic material very suitable for the cooling gas inlet tube 22.

In an embodiment, of which an example is shown in FIG. 2 , the at leastone cooling gas supply 22 comprises a plurality of cooling gas supplieswhich are evenly spaced around the core tube 12. By evenly spacing thecooling gas supplies around the core tube 12 a uniform inflow of coolinggas along the elongated circumferential wall 14 may be obtained.

In an embodiment, of which an example is shown in FIG. 1 , the verticalbatch furnace assembly 10 may further comprise at least one cooling gasdischarge 30 comprising at least one discharge opening 31 to dischargethe cooling gas from the cooling chamber 20. In operation, the emanatedcooling gas may flow from the at least one cooling gas supply along theelongated circumferential wall 14 of the core tube 12 to the at leastone cooling gas discharge 30.

The at least one cooling gas discharge 30 may comprises a plurality ofcooling gas discharges 30 which are evenly spaced around the core tube12. By evenly spacing the cooling gas discharges 30 around the core tube12 a uniform outflow of cooling gas along the elongated circumferentialwall 14 is obtained.

As shown in FIG. 1 , the at least one cooling gas supply may be arrangedat or near a first longitudinal end 32 of the cooling chamber, and theat least one cooling gas discharge 30 may be arranged at or near asecond longitudinal end of the cooling chamber 34. In this way thecooling gas will flow parallel to the longitudinal direction along theelongated circumferential wall 14 as indicated with the arrow F.

The vertical batch furnace assembly 10 may further comprise a coolinggas recirculation channel 36 extending from the at least one cooling gasdischarge 30 to the at least one cooling gas supply 22. The cooling gasrecirculation channel 36 may comprise a pressure increasing device 38,such as a fan or blower, and a heat exchanger 40 configured to cool thecooling gas in the recirculation channel 36. By recirculating thecooling gas, the cooling gas is re-used, which means no new cooling gashas to be supplied. This is especially advantageous when the cooling gasis not the ambient air, but e.g. concentrated nitrogen which has to bebought, and of which the supply can run out. Furthermore, by notconstantly introducing new cooling gas into the cooling chamber 20,debris or pollution does not enter the cooling chamber 20 either. Alsohazardous pollution originating from the cooling chamber or other partsof the vertical batch furnace assembly 10 are not emitted to thesurroundings together with the cooling gas.

Preferably, the pressure increasing device 38 may be arranged downstreamof the heat exchanger 40. It may be desired to have the pressure at thecooling gas supply opening 26 at a certain level. By having the pressureincreasing device 38 arrange downstream of the heat exchanger 40, thepressure increasing device 38 needs less power to achieve a certainpressure at the cooling gas supply opening 26, as opposed to anarrangement wherein the pressure increasing device 38 is arrangedupstream of the heat exchanger 40.

The configuration of the at least one cooling gas discharge 30 may besimilar to the configuration of the at least one cooling gas supply,wherein the flow direction of the cooling gas within the cooling chamber20 is reversible. The at least one cooling gas discharge opening may beconfigured such that, when the flow direction of the cooling gas withinthe cooling chamber 20 is reversed and the cooling gas discharge openingserves as a cooling gas supply opening 26, the cooling gas enters thecooling chamber 20 with a flow direction which is substantially tangentto the circumferential wall 14.

The cooling gas may cool the core tube 12 by absorbing heat from saidcore tube 12. When flowing in one direction, the cooling gas is coldestwhen entering the cooling chamber 20 and warmest when exiting via thecooling gas discharge 30. This means that part of the circumferentialwall 14 closest to the cooling gas discharge 30 will be cooled to alesser extent by the cooling gas than the part of the circumferentialwall 14 which are closer to the cooling gas supply tubes 22. In order toincrease the overall cool down speed of the elongated circumferentialwall 14, it may be beneficiary to have the cooling gas also flow fromthe cooling gas discharge 30 towards the cooling gas supply. The coolinggas may then flow for a certain time from the cooling gas supply alongthe circumferential wall 14 to the cooling gas discharge 30 therebyprimarily cooling part of the circumferential wall 14 nearest thecooling gas supply. After said certain time the flow direction may bereversed and the cooling gas may flow a certain time from the coolinggas discharge 30 along the circumferential wall 14 to the cooling gassupply 22 thereby primarily cooling part of the circumferential wall 14nearest the cooling gas discharge 30. In this way the overall coolingefficiency of the cooling gas flow is increased.

In the example shown in FIG. 1 , this inversion of flow may be effectedin that the inlet of pressure increasing device 38 may be connected totwo suction parts 36 b of the recirculation channel 36. Each suctionpart 36 b may include a discharge valve 52 a, 52 b. An outlet of thepressure increasing device 38 may be connected to a pressure part 36 aof the recirculation channel 36. The supply part 36 a of the cooling gasrecirculation channel 36 is split in two parts and each part maycomprise diverter valve 42 a, 42 b. In use, only one of the suctionparts 36 b may be operative transport cooling gas and the other one maybe closed off by the associated discharge valve 52 a or 52 b. Bycleverly switching the diverter valves 42 a, 42 b and the dischargevalves 52 a, 52 b the cooling gas may either be directed to the at lastone cooling gas supply 22, and subsequently via the cooling chamber 20to the at least one cooling gas discharge 30 or, alternatively, to theat least one cooling gas discharge 30, and subsequently via the coolingchamber 20 to the at least one cooling gas supply 22.

Apart from being functionally the same, the cooling gas discharge 30 mayalso be structurally the same as the cooling gas supply 22. This isadvantageous for building said cooling gas discharge 30 and cooling gassupply 22, because only one type of part needs to be manufactured.

The present disclosure may also provide a method for cooling a verticalbatch furnace. The method may comprise providing a vertical batchfurnace 10 according to the description, and supplying a cooling gas inthe cooling chamber 20 with a flow direction which is substantiallytangent to the circumferential wall 14.

In an embodiment, the substantially tangent flow direction includes anangle with the longitudinal direction L of the elongated circumferentialwall 14 in the range of 90°±15°.

In an embodiment, the substantially tangent flow direction includes anangle in the range of 0°±10° with a plane through a point of thecircumferential wall that is closest to a said respective cooling gassupply opening 26 and that is tangential to the circumferential wall 14.

With an initial flow which is tangent to the circumferential wall 14,the cooling gas will not immediately flow along the longitudinaldirection L of the elongated circumferential wall 14, but instead willbe distributed in a tangential direction of the circumferential wall 14.Only after the cooling gas has been distributed in the tangentialdirection of the circumferential wall 14, the cooling gas will flow inthe longitudinal direction L along the elongated circumferential wall14. In this way there are no cold spots formed, and the disadvantagesassociated with these so-called cold spots are prevented.

Although illustrative embodiments of the present invention have beendescribed above, in part with reference to the accompanying drawings, itis to be understood that the invention is not limited to theseembodiments. Variations to the disclosed embodiments can be understoodand effected by those skilled in the art in practicing the claimedinvention, from a study of the drawings, the disclosure, and theappended claims.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure or characteristicdescribed in connection with the embodiment is included in at least oneembodiment of the present invention. Thus, the appearances of thephrases “in one embodiment” or “in an embodiment” in various placesthroughout this description are not necessarily all referring to thesame embodiment.

Furthermore, it is noted that particular features, structures, orcharacteristics of one or more of the various embodiments which aredescribed above may be used implemented independently from one anotherand may be combined in any suitable manner to form new, not explicitlydescribed embodiments. The reference numbers used in the detaileddescription and the claims do not limit the description of theembodiments, nor do they limit the claims. The reference numbers aresolely used to clarify.

LEGEND

-   10—vertical batch furnace assembly-   12—core tube-   14—circumferential wall-   16—outer casing-   18—heating element-   20—cooling chamber-   22—cooling gas inlet tube-   24—end part (of the cooling gas inlet tube)-   26—cooling gas supply opening-   28—axial end (of the cooling gas inlet tube)-   30—cooling gas discharge-   32—first longitudinal end (of the cooling chamber)-   34—second longitudinal end (of the cooling chamber)-   36—cooling gas recirculation channel-   38—pressure increasing device-   40—heat exchanger-   42 a—diverter valve-   42 b—diverter valve-   44—opening (in the outer casing)-   46—cam-   48—recess-   52 a—discharge valve-   52 b—discharge valve-   L—longitudinal direction

The invention claimed is:
 1. A vertical batch furnace assembly,comprising: a core tube having an elongated circumferential wallextending in a longitudinal direction, wherein the core tube isconfigured to accommodate wafers for processing in the vertical batchfurnace assembly; an outer casing extending around the core tube andcomprising a heating element for applying a thermal treatment to wafersaccommodated in the core tube; a cooling chamber bounded on a radialouter side by the outer casing and on a radial inner side by the coretube; at least one cooling gas supply emanating in the cooling chamber,wherein the cooling gas supply comprises at least one cooling gas supplyopening which is configured such that the cooling gas enters the coolingchamber with a flow direction which is substantially tangent to thecircumferential wall; at least one cooling gas discharge comprising atleast one discharge opening to discharge the cooling gas from thecooling chamber, wherein, in operation, the emanated cooling gas flowsfrom the at least one cooling gas supply along the elongatedcircumferential wall of the core tube to the at least one cooling gasdischarge; and a cooling gas recirculation channel extending from the atleast one cooling gas discharge to the at least one cooling gas supply,the cooling gas recirculation channel comprising: a pressure increasingdevice, such as a fan or blower; and a heat exchanger configured to coolthe cooling gas in the recirculation channel, wherein the configurationof the at least one cooling gas discharge is similar to theconfiguration of the at least one cooling gas supply, wherein the flowdirection of the cooling gas within the cooling chamber is reversible,wherein the at least one cooling gas discharge opening is configuredsuch that, when the flow direction of the cooling gas within the coolingchamber is reversed and the cooling gas discharge opening serves as acooling gas supply opening, the cooling gas enters the cooling chamberwith a flow direction which is substantially tangent to thecircumferential wall.
 2. The vertical batch furnace according to claim1, wherein the substantially tangent flow direction includes an anglewith the longitudinal direction of the elongated circumferential wall inthe range of 90°±15°.
 3. The vertical batch furnace according to claim1, wherein the substantially tangent flow direction includes an angle inthe range of 0′±10° with a plane through a point of the circumferentialwall that is closest to said respective cooling gas supply opening andthat is tangential to the circumferential wall.
 4. The vertical batchfurnace assembly according to claim 1, wherein each cooling gas supplycomprises a cooling gas inlet tube of which an end part extends into thecooling chamber, wherein said end part is provided with the at least onecooling gas supply opening.
 5. The vertical batch furnace assemblyaccording to claim 4, wherein each cooling gas inlet tube is embodied asone integral part.
 6. The vertical batch furnace assembly according toclaim 4, wherein each cooling gas inlet tube is made of a ceramicmaterial.
 7. The vertical batch furnace assembly according to claim 4,wherein an axial end of the cooling gas inlet tube extending into thecooling chamber is closed off.
 8. The vertical batch furnace assemblyaccording to claim 1, wherein the at least one cooling gas supplycomprises a plurality of cooling gas supplies which are evenly spacedaround the core tube.
 9. The vertical batch furnace assembly accordingto claim 1, wherein the at least one cooling gas discharge comprises aplurality of cooling gas discharges which are evenly spaced around thecore tube.
 10. The vertical batch furnace assembly according to claim 1,wherein the at least one cooling gas supply is arranged at or near afirst longitudinal end of the cooling chamber, and the at least onecooling gas discharge is arranged at or near a second longitudinal endof the cooling chamber.
 11. The vertical batch furnace assemblyaccording to claim 1, wherein the pressure increasing device is arrangeddownstream of the heat exchanger.
 12. The vertical batch furnaceassembly according to claim 1, wherein the cooling gas recirculationchannel comprises diverter valves and/or discharge valves to direct thecooling gas either to the at last one cooling gas supply, andsubsequently via the cooling chamber to the at least one cooling gasdischarge or, alternatively, to the at least one cooling gas discharge,and subsequently via the cooling chamber to the at least one cooling gassupply.
 13. A method for cooling a vertical batch furnace, comprising:providing a vertical batch furnace according to claim 1; and supplying acooling gas in the cooling chamber with a flow direction which issubstantially tangent to the circumferential wall.
 14. The methodaccording to claim 13, wherein the substantially tangent flow directionincludes an angle with the longitudinal direction of the elongatedcircumferential wall in the range of 90′±15′.
 15. The method accordingto claim 13, wherein the substantially tangent flow direction includesan angle in the range of 0′±10° with a plane through a point of thecircumferential wall that is closest to a said respective cooling gassupply opening and that is tangential to the circumferential wall.